Nowadays the use of laundry washing machines, both “simple” laundry washing machines (i.e. laundry washing machines which can only wash and rinse laundry) and laundry washing-drying machines (i.e. laundry washing machines which can also dry laundry), is widespread.
In the present description the term “laundry washing machine” will refer to both simple laundry washing machines and laundry washing-drying machines.
Laundry washing machines generally comprise an external casing provided with a washing tub which contains a rotatable perforated drum where the laundry is placed.
A loading/unloading door ensures access to the drum.
Laundry washing machines typically comprise a water inlet circuit and a products supply unit for the introduction of water and washing/rinsing products (i.e. detergent, softener, etc.) into the tub.
Known laundry washing machines are also provided with water draining devices that may operate both during the initial phases of the washing cycle and at the end of the same to drain the dirty water.
According to the known technique, a complete washing cycle typically includes different phases during which the laundry to be washed is subjected to adequate treatments.
A washing cycle usually comprises a laundry wetting phase with addition of a washing detergent and a main washing phase during which the drum is rotated and the water contained therein is heated to a predetermined temperature based on the washing program selected by the user. During the main washing phase the drum is rotated, so as to apply also a mechanical cleaning action on the laundry. At the end of the main washing phase the drum is typically rotated at high rotational speed, in such a way that dirty washing liquid (i.e. water mixed with detergent and dirty particles) is extracted from the laundry, and this dirty washing liquid is drained by the water draining devices.
A successive step of the cycle typically comprises a rinsing phase which usually comprises one or more rinsing cycles. In the rinsing cycle, clean rinse water is first added to the laundry, so as to be absorbed by the laundry and remove from the latter detergent and/or dirty particles not previously removed by washing liquid, and then the drum is rotated to extract water and dirty particles/detergent from the laundry: the dirty water extracted is drained from the tub to the outside by the water draining devices.
After the rinsing phase, a final spinning phase allows the extraction of the residual water contained in the wet laundry.
The water extracted during the spinning phase is drained towards the outside by means of the water draining devices (during or after the spinning phase).
A laundry washing machine performing a washing cycle is disclosed in document CN101696544A.
Such laundry washing machine comprises a tub having a cylindrical structure for containing washing water and a rotary drum rotatably installed in the tub.
The machine further comprises a recirculating circuit having one recirculating pump which withdraws liquid from the bottom of the tub and re-admits such liquid at the bottom of the tub or into an upper portion of the tub.
Therefore, a first liquid circuit recirculates liquid at the bottom of the tub and a second liquid circuit recirculates liquid at the upper portion of the tub.
At this purpose, the recirculating pump outlet is connected to a three-way valve, with one inlet and two outlets, which selectively diverts liquid from the bottom of the tub again to the bottom of the tub or to the upper portion of the tub by means of respective pipes connected to the outlets.
The liquid is re-circulated at the bottom of the tub in the first liquid circuit when the dissolution of the detergent inside the tub is required.
The liquid is re-circulated in the second liquid circuit at the upper portion of the tub in order to increase the absorption of the liquid by the laundry inside the tub.
The choice between the first and the second liquid circuit is therefore carried out by properly controlling the three-way valve.